Performance analysis of IEEE 802.11 ad hoc networks in the presence of exposed terminals

The paper evaluates the performance effects of exposed terminals in IEEE 802.11 ad hoc networks in finite load conditions. It derives analytical models for the estimation of channel utilization and media access delay for IEEE 802.11 ad hoc networks in finite load conditions with and without exposed terminals. The simulation results show that the analytical estimated channel utilization and media access delay metrics are fairly accurate.     

Exergoeconomic analysis and evaluation of energy-conversion plants—I. A new general methodology

A new approach to the combination of exergetic and economic analysis (exergoeconomic analysis) for the investigation of energy-conversion processes is presented. This approach allows the monetary evaluation of costs caused by irreversibilities (exergy losses), as well as comparisons between these costs and the investment and operating costs for each component of a plant. The present analysis permits identification and evaluation of inefficiencies in an energy-conversion plant and of opportunities for improvement.     

The Gestational Effects of Maternal Bone Marker Molecules on Fetal Growth,Metabolism and Long-Term Metabolic Health: A Systematic Review

Fetal exposure in adverse environmental factors during intrauterine life can lead to various biological adjustments, affecting not only in utero development of the conceptus, but also its later metabolic and endocrine wellbeing. During human gestation, maternal bone turnover increases, as reflected by molecules involved in bone metabolism, such as vitamin D, osteocalcin, sclerostin, sRANKL, and osteoprotegerin; however, recent studies support their emerging role in endocrine functions and glucose homeostasis regulation. Herein, we sought to systematically review current knowledge on the effects of aforementioned maternal bone biomarkers during pregnancy on fetal intrauterine growth and metabolism, neonatal anthropometric measures at birth, as well as on future endocrine and metabolic wellbeing of the offspring. A growing body of literature converges on the view that maternal bone turnover is likely implicated in fetal growth, and at least to some extent, in neonatal and childhood body composition and metabolic wellbeing. Maternal sclerostin and sRANKL are positively linked with fetal abdominal circumference and subcutaneous fat deposition, contributing to greater birthweights. Vitamin D deficiency correlates with lower birthweights, while research is still needed on intrauterine fetal metabolism, as well as on vitamin D dosing supplementation during pregnancy, to diminish the risks of low birthweight or SGA neonates in high-risk populations.     

Clustering‐based scheduling: A new class of scheduling algorithms for single‐hop lightwave networks

In wavelength division multiplexing (WDM) star networks, the construction of the transmission schedule is a key issue, which essentially affects the network performance. Up to now, classic scheduling techniques consider the nodes' requests in a sequential service order. However, these approaches are static and do not take into account the individual traffic pattern of each node. Owing to this major drawback, they suffer from low performance, especially when operating under asymmetric traffic. In this paper, a new class of scheduling algorithms for WDM star networks, which is based on the use of clustering techniques, is introduced. According to the proposed Clustering‐Based Scheduling Algorithm (CBSA), the network's nodes are organized into clusters, based on the number of their requests per channel. Then, their transmission priority is defined beginning from the nodes belonging to clusters with higher demands and ending to the nodes of clusters with fewer requests. The main objective of the proposed scheme is to minimize the length of the schedule by rearranging the nodes' service order. Furthermore, the proposed CBSA scheme adopts a prediction mechanism to minimize the computational complexity of the scheduling algorithm. Extensive simulation results are presented, which clearly indicate that the proposed approach leads to a significantly higher throughput‐delay performance when compared with conventional scheduling algorithms. We believe that the proposed clustering‐based approach can be the base of a new generation of high‐performance scheduling algorithms for WDM star networks. Copyright © 2008 John Wiley & Sons, Ltd.     

Special Issue on the Internet of Things (ISCC 2020)

Journal of Signal Processing Systems -     

Semi-Supervised Deep Learning for Multi-Tissue Segmentation from Multi-Contrast MRI

Journal of Signal Processing Systems - Segmentation of thigh tissues (muscle, fat, inter-muscular adipose tissue (IMAT), bone, and bone marrow) from magnetic resonance imaging (MRI) scans is useful...     

On Supporting Secure Information Distribution in Heterogeneous Systems Using Standard Technologies

This paper presents an integrated security architecture for heterogeneous distributed systems. Based on the MPEG-21 standard data structures and the MPEG-M standard services, the proposed architecture provides a unified, fine-grained solution for protecting each information unit circulated in the system. In this context, a novel scheme for translating the access control rules, initially expressed by means of the standard MPEG-21 Rights Expression Language, into Ciphertext-Policy Attribute-Based Encryption access trees is introduced, thereby enabling offline authorization based on the users’ attributes, also encapsulated and certified using MPEG-21 licenses. The proposed framework provides a detailed approach in all the steps of the information protection process, from attribute acquisition to data encryption and decryption.     

Ultralong 20 Milliseconds Charge Separation Lifetime for Photoilluminated Oligophenylenevinylene–Azafullerene Systems

The synthesis and characterization of oligophenylenevinylene (OPV)–azafullerene (C₅₉N) systems in the form of OPV–C₅₉N donor–acceptor dyad 1 and C₅₉N–OPV–C₅₉N acceptor–donor–acceptor triad 2 is accomplished. Photoinduced electronic interactions between OPV and C₅₉N within 1 and 2 are assessed by UV–vis and photoluminescence. The redox properties of 1 and 2 are investigated, revealing a set of one‐electron oxidation and three one‐electron reduction processes owed to OPV and C₅₉N, respectively. The electrochemical bandgap for 1 and 2 is calculated as 1.44 and 1.53 eV, respectively, and the free energy for the formation of the charge‐separated state for 1 and 2 via the singlet‐excited state of OPV is found negative, proving a thermodynamically favorable the process. Photoexcitation assays are performed in toluene and o‐dichlorobenzene (oDCB) and the reactions are monitored with time‐resolved absorption and emission spectroscopies. Competitive photoinduced energy and electron transfer are identified to occur in both systems, with the former being dominant in 2 . Markedly, the charge‐separated state in oDCB exhibits a much longer lifetime compared to that in toluene, reaching 20 ms for 1 , the highest ever reported value for fullerene‐based materials. These unprecedented results are rationalized by considering conformational phenomena affecting the charge‐separated state.